Most of the time, the planes swoop down without warning to unleash death and destruction: a busload of children on their way to school, mourners at a funeral and guests at a wedding party, a family of six asleep in their beds — they are all examples of the tens of thousands of Yemenis killed or injured in deadly airstrikes that target them for no apparent military reason.
In Yemen, each new day brings "a new face of tragedy," Ali Jameel told DW on a crackling phone line from the capital, Sanaa.
When it comes to tragedy, Jameel is an expert: He works for a Yemeni human rights organization, Mwatana, that despite the odds and risks its researchers face, including arbitrary detention, painstakingly documents human rights violations committed by both sides in a conflict that has been dragging on for more than three years.
It started in late 2014 with protests against the government by Houthi rebels, which belong to an offshoot of Shia Islam.
Yemen: 'We're living in hell'
The protests quickly turned into a full-scale rebellion, forcing the government into exile in Saudi Arabia. In response, and most likely also sensing an opportunity to weaken its arch rival Iran, which it perceived as supporting the Houthis, Riyadh stepped into the fray in March 2015.
Since then, the Saudi-led coalition has been waging its devastating air campaign on areas held by Houthi and other forces and the death toll is rising: According to the Armed Conflict Location & Event Data Project (ACLED), a database that tracks armed conflicts, at least 57,000 people have been reported dead since early 2016.
Read more:Yemen's war explained in 4 key points
"We're living in hell," one Yemeni aid worker in Hodeida, the country's blockaded main harbor, told DW. He spoke of his constant insomnia, as the fear of attacks keep him awake night after night.
It's a hell that's being fueled by weapons produced by international and European arms companies.
For them, it's a lucrative conflict. For years, Saudi Arabia has been one of the German arms industry's top clients, making Germany the fourth largest exporter of weapons to the kingdom after the United States, Britain and France.
Riyadh is Germany's second-best arms customer
From January to September of this year, Germany approved arms exports worth €416.4 million ($472.6 million), which makes Saudi Arabia Germany's second-best arms customer after Algeria.
In October, the German government gave the green light for further exports to Saudi Arabia worth some €254 million.
It runs against the fact that Germany has some of the most restrictive arms export controls. And, on top of that, the governing parties signed a coalition agreement earlier this year which says that no weapons exports may be approved to any country "directly" involved in the war in Yemen. There is a caveat, however, if companies can prove that the weapons delivered will remain in the country that they are sold to.
Until recently, the government seemed to take the view that the agreement exempted deals struck with countries before the coalition agreement.
That is why Angela Merkel's grand coalition maintained the approval it had granted in 2015 for the export of several military patrol vessels to Saudi Arabia built by the Peene shipyard in Wolgast, a small town in northeast Germany, owned by the Luerssen corporation.
This was seen as particularly controversial because the boats may have been used in the blockade of the Hodeida harbor, Yemen's most important port.
Despite a pro-government offensive, it is still being held by the Houthis and serves as the main entry point for more than 80 percent of the country's imports and humanitarian aid.
The blockade has lead to a humanitarian crisis, pushing up the price for fuel, food and medicine. As inflation skyrockets, even basic food items have become too expensive for most Yemenis.
Millions are facing starvation.
According to the aid group Save the Children, 85,000 children under five may have died of hunger or disease in what the UN terms the world's worst humanitarian crisis.
Are German-made vessels part of the blockade?
DW is aware of at least three German-made patrol vessels which seem to have turned off their transponders — an indication, many believe, that they may have crossed into Yemeni waters. DW has not been able to verify whether they have indeed been used directly in the blockade.
Researcher Ali Jameel says his organization has documented several attacks on fishing vessels close to Hodeida, but has only been able to definitely link one of them to an Apache II helicopter, not any boats, let alone German ones.
But, experts agree, even if the German patrol boats are not actively engaged in the conflict, it is likely that they are at the very least freeing resources and ships more suitable for the blockade. And in a recent parliamentary debate in Berlin, opposition politicians vented their outrage that the vessels had been allowed to be exported at all.
In late October, however, the controversial exports were put on hold following the death of journalist Jamal Khashoggi in the Saudi consulate in Istanbul, which many believe is likely to have been sanctioned by Saudi Crown Prince Mohammed bin Salman.
At the time, Chancellor Merkel pointed to the unexplained circumstances of Khashoggi's death. Arms exports, she said, could not proceed given "the situation we are currently in".
However, Germany also makes components for multinational European export contracts, including for a multi-billion dollar agreement with Saudi Arabia to buy 48 new EurofighterTyphoon fighter jets from the UK. Roughly a third of the components, including larger parts but also small items such as bolts, are supplied by Germany, experts say.
Those exports may also be on hold, DW has learned. Suppliers, one source told DW, had received official letters requesting them to desist from exporting for the time being.
Both the German defense and economics ministries were unwilling to comment on the question of German components.
The temporary ban is reportedly limited to two months. And opposition politicians from the Left Party and the Greens told DW they are convinced the ban will soon be lifted.
For Saudi Arabia has long been a special partner for Western governments, including Germany, who consider the kingdom a "strategic" partner in the Middle East that government ministers like to describe as an "anchor of stability" in the region.
Saudi Arabia 'has a free pass'
Yet there is ample evidence that Saudi Arabia has long been exporting its ultra orthodox, intransigent interpretation of Islam across the globe and has stoked several regional conflicts.
None of this seemed to duly bother Western officials until now. Given its vast oil reserves and history of strong political ties, Saudi Arabia "can do whatever it wants. It has a free pass," Andrew Feinstein, a leading arms expert and executive director of Corruption Watch, told DW.
Germany, he said, had a restrictive arms exports policy "only when it suits Germany" — and in the case of Saudi Arabia, for many years, it clearly didn't.
And, off the record, one official admitted that the German government is happy for other European countries to export weapons to Saudi Arabia, even if Germany's hands are bound by its decision to temporarily halt all exports. Germany, the official said, had a strong interest in Saudi Arabia's stability, implying that it could only be guaranteed by a steady flow of arms.
But, even with the export ban in place, German-made and designed arms are still ending up in Yemen.
German-designed bombs in Yemen
One example of several is Rheinmetall, a German arms corporation based in the western German city of Dusseldorf. One of its subsidiaries, RWM Italia, builds bombs on the Italian island of Sardinia. Ali Jameel and his team at Mwatana have been able to prove that in October 2016 a family of six, including a pregnant woman, was killed by a bomb produced by RWM Italia.
There was, according to eyewitnesses interviewed by Mwatana, no military reason for the airstrike that was launched at three in the morning when the family was asleep in their house. DW has obtained a copy of the case report which calls the airstrike "a crime."
In April 2018, Mwatana and several European human rights organizations filed a criminal complaint against managers of RWM Italia and senior officials of Italy's National Authority for the Export of Armament.
The case is ongoing, but it is likely, activists told DW, that while prosecutors decide whether to investigate, RWM would continue exporting to Saudi Arabia.
Indeed, DW has learnt, the bomb factory is planning to expand and has asked the local authorities for planning permission.
Saudi Arabia is trying to build its own arms industry
In a meeting with investors earlier this year, the CEO of Rheinmetall, Armin Papperger, reportedly stressed that his company was not responsible for any business conducted by its subsidiaries.
Meanwhile, Saudi Arabia has embarked on a drive to build a domestic arms industry. One example is its factory which produces G36 assault rifles with a license it bought from the southern German company Heckler and Koch in 2008.
More recently, it is seeking a broad partnership with the struggling South African arms maker Denel, which would include acquisition of the company's minority stake in a joint venture Denel holds with German Rheinmetall: Rheinmetall Denel Munition (RDM).
RDM specializes in medium and large-caliber ammunition including artillery shells.
Should the deal go through, it would be another step towards making the Saudi kingdom less dependent on direct foreign arms exports, while relying on German technological knowhow.
In the meantime, weapons continue to pour into the conflict that has pushed, as one Yemeni academic told DW, an already impoverished country firmly back "into the middle ages."
"As long as weapons fuel the war, it will never end," Ali Jameel from Mwatana told DW.
He recalled the fear on the faces of the people he meets when he heads out to document the carnage wrought by each airstrike.
"Everyone is afraid," he said. "They know: Today it is not my house, but tomorrow it will be."
Another Yemeni source had one request: "Pray for us," he begged DW. "Pray for this war to stop."